Smart Hybrid Energy Storage for Stand-alone PV Microgrid: Optimization of Battery Lifespan through Dynamic Power Allocation

摘要

Battery as the key component in stand-alone PV microgrid system tends to be the most vulnerable element in terms of durability. Poorly managed battery charge/discharge process turns out to be one of the main life-limiting factors. To improve the longevity of battery storage system, a novel energy storage system topology and its smart power management strategy is presented in this paper. This paper proposes a stand-alone 6 kW PV microgrid system with hybrid energy storage system that combines supercapacitors and batteries. Smart power allocation strategy among the SC and the battery modules is designed to dynamically allocate the power to optimally charge/discharge the batteries while fulfilling the variations in supply and load. The performance of the proposed system is evaluated via model simulation using Matlab/Simulink. The system is simulated under a typical 24-hours residential load profile and the results proved that the proposed system can provide sufficient power to regulate the fluctuations in supply and load. During the process, the batteries are charged/discharged with ideal charge rate and operated under a low depth-of-discharge that have proven to prolong the battery lifetime.